Corrugated board



Patented Feb. 27, 1934 UNITED STATES CORRUGATED BOARD Charles L. Keller, Cincinnati, Ohio, assignor to The Richardson Company, Lockland, Ohio, a

corporation of Ohio No Drawing. Application 2,1928

Serial No. 289.933.

1 Claim.

. ture because of the cost of the ingredients. Or-

dinary corrugated board, on the other hand, is not satisfactory as insulation for many reasons, chief among which is the fact that it deteriorates with age and under the influence of moisture.

36 Furthermore, in its use in the manufacture of container stock, corrugated board has certain disadvantages in that the filler ply, the ply which receives the corrugations, must be of stifi material, and hitherto the only generally accepted 80 material has been a straw board. There have been many endeavors to substitute other materials for straw board in the filler plies of corrugated sheets, but no other material has met with wide acceptance.-

2 Secondly, corrugated board is not waterproof or moistureprooi, and deteriorates under dampness. It is uneconomical to waterproof corrugated board which has already been formed, and structural considerations make it impossible to use as the 80 filler ply such waterproofed materials as have hitherto been suggested. Nor has economical success attended the use of waterproofed liner plies.

My object is to provide a new corrugated board 85 in which the filler ply will have. greater stiffness and strength, which will be permanent in its character and moisture resistant, and which willbe suitable for house insulation, as well as for the manufacture of containers which will afford 40 the contents thereof greater protection than is ordinarily afforded by corrugated boards.

It is also my object to produce a cheap and efficient substitute for straw board in corrugated boards.

These and other objects which will become apparent to one skilled in the .art upon reading these specifications, I accomplish by my invention, which I shall now describe more in detail.

In practicing my invention I take, as an example 30 parts by weight of news print or other waste paper and after wetting the paper, I place it in a mixer into which I introduce, say parts by weight of an asphaltic material. The asphaltic material may vary in its properties, as determined 5 by penetration and ball and ring softening point Some cortests, in accordance with the desired qualities in the finished product; but it should preferably be of such character as to become viscous and gummy at or below the boiling point of water.

I apply heat to my mixer, and this heat will 6. tend to soften the asphalt and evaporate the water from the paper fibers. The evaporation of the water, however, cools the mass so that the resultant heat in the material as it is being mixed will not be very much, if at all, above the boiling point of water. At this temperature, as indicated, the asphaltic material should be gummy, l. e., strongly adhesive to the fibrous masses and more extensible than they, whereby when I knead the mass in the mixer in such a way as to '0 repeatedly extend it, the fibrous aggregates will be broken down into individualized fibers and these fibers homogeneously distributed and refelted in themass of binder. In ordinary practice I prefer to use a Werner & Pfleiderer mixer 7 or mixer of like type, and the mixing method I have just described is the one described and claimed by James C. Woodley in Patent No. 1,156,122.

Having disintegrated the waste paper materials 30 into individualized fibers which are distributed throughout the mass of asphaltic binder so that the whole has assumed a fibrous character, I then add to the mixer a quantity of water and continue the mixing action. The asphaltic mass 95 will gradually break down and come into suspension in the water under the influence of the continued mixing action, the suspension comprising comparatively small masses of fibrous asphalt. This may be done with or without a lubricating agent, the pulp-forming process in general being fully described in the application of Harry 0. Fisher, Serial No. 314,551, filed October 23, 1928.

When I have thus obtained a suspension which a Fourdrlnier wire or cylinder mould as ordinary paper stock is formed.

A modified way 01' making a bituminous pulp is set forth in the co-pending application of Earl P. Stevenson and Harry A. Buron, Serial No.

316,611, filed November 1, 1928.

This treat- I desire it to be understood that in making this pulp I am not restricted to the use of any particular type of mixer, beating or Jordan engine, or any particular percentages of ingredients; that the kind and character of my asphaltic materials and fibrous materials may be varied to suit different uses, and that other materials may be added to the finished or partly finished pulp. I may also add in the beating engine a quantity or ordinary fibrous material or pulp with which no asphalt'is associated.

The type of pulp which I prefer to use is the one produced by the process described, i. e., a true bituminous pulp which is obtained by following the processes of the copending applications to which I have referred, both of which processes antedate my disclosure. It is a pulp in which the fibers are associated in the pulp itself with the asphaltic material, as distinguished from a pulp of fibers in which asphaltic materials are merely held in suspension; although I am not restricted to this type of pulp alone. Neverthe less I find it by far-the most advantageous to use, for the reason that it gives in finished and dried form a sheeted and felted article which, dependent upon the amount of binder therein, partakes of the nature of a plastic composition, and also because in this process I can associate the minimum amount of fibers required for strength and toughness with the maximum amount of binder material for protection, stiiI- ness, rigidity, waterproofness, and the like. Furthermore this type of pulp gives no trouble on the screen and there is no appreciable loss of binder caused by unattached particles thereof washing through the screen.

Of this material I form a sheet on a Fourdrinier or cylinder mould paper machine, the sheet beng of a caliper suitable for the manufacture of corrugated board. As the formed sheet passes over the driers the water is expelled therefrom and the asphaltic binder consolidates the sheet into a tough and resilient product. By proper selection of the amount and character of the asphaltic binder employed the sheet may be made more or less stiff as desired, while the selection of the amount and character of the fibrous material will largely determine the strength of it. In this fashion I may form a sheet of material which is asphalt-saturated, permanent and waterproof, which is no thicker in caliper than straw board used for a like purpose, which has an equivalent or a greater stiffness, and which may serve as a straw board substitute with many advantages.

For ordinary container use, it will be sufficient to take a sheet of this product of suitable thickness and use it as the inner or corrugated liner. The operation of forming the corrugated board of my new product does not differ at all from ordinary corrugating operations, the asphaltic sheet passing through the corrugating rolls and being cemented between the liners in the ordinary fashion. Silicate of soda is ordinarily used, and works quite well in my product. I prefer it to an animal glue because of its greater permanency and its lessened susceptibility to moisture. Other adhesives may, however, be used, such as glues or even asphaltic and bituminous materials. With outer liners of chip board or the like and an interliner of the asphaltic pulp product, I secure a corrugated board for container use which is very little affected by atmospheric conditions and which will afford protection to the contents of the container which is not afforded by the present commercial product.

Where it is desirable, however, to make a product which is completely waterproof, I may use the asphaltic pulp product not only for the corrugated filler, but also for the liners, manufacturing the board in the same way and using the same adhesive. Or I may, if desired, use a super-added bituminous adhesive or merely fuse together the sheets and bond them under heat or heat and pressure by means of their contained asphalt.

Where the liner sheets are the same in stiffness as the filler sheet, a very still and rigid product results. In ordinary practice I may prefer to use an asphaltic pulp sheet for my liners of different characteristics than I employ for the filler, the liners being softer. This corrugated product is not only useful for the manufacture of containers, but finds a wide field of adaptation in the insulation of building structures from heat and cold. Its efficiency for this purpose is very high by reason of the dead air spaces existing in the corrugations. It is also light in weight and does not add appreciably to the weight of the structure to which it is applied or necessitate the use of heavier structural members. It is permanent because it is not greatly affected by moisture and atmospheric conditions, and is waterproof.

For insulating purposes also I may prefer to build a very thick product by the superposition of corrugated sheets orthe manufacture of a composite product comprising successively a liner sheet,a corrugated filler sheet, a liner sheet, a second filler sheet with the corrugations running at right angles to the corrugations of the first, another liner sheet, et cetera. There may be built up in this way a board of any desired thickness and of great insulating capacity which is suitable for all building purposes where it does not have to sustain a weight greater than the inherent strength of the corrugations.

Althoughthe ordinary methods of making corrugated boards are applicable to the manufacture of my new product, the nature of the sheet I use makes possible the production of types of corrugated product hitherto impossible. The sheeted product formed as described from an asphaltic or bituminous pulp partakes of the nature of a plastic composition in that it may be readily moulded under heat and pressure. Thus, instead of pressing corrugations into it by cold rolls, I may deform it by means of hot rolls into any shape desired. I may form corrugations in the material in which the parts of the corrugated structure which stand the greatest strain are made thicker than other parts. I may plastically mould into corrugated form a sheet much heavier than could otherwise be used, forming in this way a corrugated structure of great strength, suitable for sustaining weight. Such a product may be used beneath roofing as insulation and may be walked upon without detriment. Again, I need not form parallel corrugations in my sheets, but may form in them any configurations suitable for strength, insulating capacity, or other desired qualities. Thus, for insulation I may prefer to form a cellular structure rather than a corrugated structure, so as to produce closed dead air cells. Instead of rolls, of course, other well-known means may be used to deform the sheet.

Owing to the high price of cork and similar insulating materials for house protection, there have been many proposals to form insulation from corrugated board, but these have uniformly so far as I am aware been unsuccessful. first, because ordinary corrugated board is not waterproof and is subject to deterioration, and, second, because it cannot economically be treated in any manner to give it the required characteristics. I have succeeded in solving the problem of manufacturing house insulation from cheap corrugated materials. My product is not characterized by deterioration under use or by the sticky surface formed when ordinary products are coated with a bitumen, as has been proposed. My product is preferably not coated, but is composed of a fibrous asphaltic composition. In one aspect of my invention I have succeeded in rendering bituminous compositions suitable for insulation by giving them a cellular character. 

